echinodermatagroupF - Class Echinoidea (Sea Urchins)

Echinoidea, or sea urchins, have radial symmetry, an external chitinous skeleton and a central jaw with teeth, known as Aristotle's lantern. The anus of sea urchins is located on the upper surface. Some sea urchins have a cloaca that extends out of the anus to excrete waste. Sea urchins move by using a tube foot that extends to pull the urchin along. Some urchins also use their spines to help with movement.

Sourceshttp://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul00/urchin1.htmlhttp://library.thinkquest.org/J001418/urchin.htmlhttp://www.dailygalaxy.com/photos/uncategorized/urchins_1.jpg